1. Field of the invention:
The present invention relates to a computer, and more particularly, to a small electronic computer such as a hand-held calculator, an electronic organizer, a scientific calculator, or the like.
2. Description of the prior art:
Generally, a small electronic computer such as a hand-held calculator is designed to be capable of temporarily storing numeric data or a calculation result in a memory and performing calculation by using the numeric data thus stored in the memory.
FIG. 6 shows an example of an operation scheme of a calculation in a hand-held calculator in which such a memory function is used. The example shown in FIG. 6 is a calculation of "2 + (Memory)", where "(Memory)" denotes the contents of a data stored in a memory ("123" in this case). The calculation operation is executed in the following sequence:
(1) A numeric value "123" is stored in the memory. PA0 (2) The display is cleared. PA0 (3) "2 +" is input. PA0 (4) The numeric value stored in the memory is read out therefrom to be set as an operand. PA0 (5) An equal [=] key is pressed to execute the calculation, and the result is displayed. PA0 (1) A memory [MEMO] key is pressed to set the mode of the calculator to the data storage mode. PA0 (2) A data name ("DOLLAR" in this case) is input. PA0 (3) A cursor key is operated so as to enable the input of the contents of a data. PA0 (4) The contents of the data "123" are input. PA0 (5) An entry [ENT] key is pressed to store the input data. PA0 (6) A forward data search [.gradient.] key is pressed to retrieve the desired data by the data name "DOLLAR". The retrieved data is displayed. PA0 (7) A plus [+] key is pressed to make the calculation the state "(Memory) +". PA0 (8) A numeric key "2" is pressed to execute the calculation of "(Memory) +2".
Such a hand-held calculator is also capable of executing the calculation in the sequence reverse to that shown in FIG. 6 (i.e., the calculation of "(Memory) + 2").
Another small computer such as a hand-held scientific calculator is designed to be capable of attaching a data name to a numeric data when storing the numeric data in a memory, and to be further capable of sorting and/or retrieving the data by the data name. FIG. 7 shows an example of an operation scheme of a calculation of "(Memory) + 2" in such a scientific calculator in which a numeric data with a data name attached thereto is stored in a memory. The calculation operation is executed in the following sequence:
With the memory function used in such a conventional calculator, it is possible to store numeric data itself, but it is not possible to store it with a data name attached thereto. Therefore, the user must memorize the meaning of the stored data, thus increasing the possibility that the user cannot understand the meaning of the retrieved data.
On the other hand, in a computer capable of storing data with a data name attached thereto, it is impossible to retrieve a desired data by a data name in the course of a calculation to use it in the calculation. Thus, such a computer cannot execute a calculation requiring the input of a data after an operator (e.g., "2 + (Memory)"). Therefore, such a computer requires that the data be retrieved by a data name at the beginning of an arithmetical expression (e.g., "(Memory) + 2"), resulting in that the memory function may not be used depending on the contents of the expression.
Furthermore, when there arises a need to store other data in the memory in the course of inputting an expression in the calculation mode, it has not been possible to input or store that data without once exiting the calculation mode.